Peter, you're right, in PSX's CPDLC model one cannot arm multiple reports at the same time. But, just to avoid a misunderstanding: You can arm one report in each "report category" at the same time. I.e. the arming feature is not completely unavailable.

A tip for on the onboard engineer who's currently in the galley: You can erase that red EGT box on Instructor > Situation > Service with the button "Erase latched messages". The pod strike on the last landing caused a momentary EGT peak :-)

Perhaps you didn't see any report functions because ATC didn't request a report? The REPORT> promt at 6R appears only if the request is a "report" request. The type of request determines what types of replies are available (reject, standby, accept, report).